The operating environment of an energy cell or battery can appreciably affect its output efficiency and lifespan. For example, batteries generate more power per recharge, have a greater peak power, have a longer operating interval between recharges, and have a greater operational lifespan when used within a moderate range of temperatures. When exposed to sub-optimal or cooler temperatures, battery efficiency is reduced, potentially lowering the energy output, such as the voltage and current supplied. Conversely, prolonged exposure to temperatures above an optimal range may shorten battery life.
Most batteries generate power with an electrolytic process in a liquid solution. If the temperature of the battery is above a preferred operating temperature range associated with the battery, the liquid will quickly dry out and electrodes of the battery will be damaged or worn out. Peaks in the temperature of the battery, even of relatively short durations, can therefore shorten the operating lifetime of the battery immensely. If, instead, the battery temperature is below the preferred operating temperature range, performance of a galvanic process in the battery is degraded, thereby causing a decrease in voltage and charge holding capacity of the battery. Consequently, the battery will have to be recharged more often, resulting in a reduction in the operational life of the electrodes of the battery.
Phase change materials (PCM) are commonly used to manage and regulate the temperature of objects in relation to the object's ambient environment. A PCM has an appreciable latent heat of fusion, and is formulated to have a constant melting temperature (Tm) within the desired operating temperature range of the object to be regulated. Depending upon ambient temperatures and/or temperatures within the object, the PCM absorbs heat from, or releases heat to the object as needed at a substantially constant melting temperature, Tm, to provide the object with improved temperature stability, maintaining it for longer periods of time within its optimal operating temperature range. In general, when PCMs reach the temperature at which they change phase (their melting temperature) they absorb large amounts of heat at an almost constant temperature. The PCM continues to absorb heat without a significant rise in temperature until all the material is transformed to the liquid phase. When the ambient temperature around a liquid material falls, the PCM solidifies, releasing its stored latent heat.
Electric and hybrid vehicles, powered with energy cells employing battery technologies, are subjected to a wide range of temperatures above and below the optimal operating conditions of the vehicle batteries. PCM, which have Tm optimized for the optimal operating temperature range of batteries used in vehicles of approximately 80 F, are generally salt hydrates which are highly corrosive to their containment materials.
Thus, there exists a need for materials that are more robust than thermoplastics for containing PCM in temperature regulation and management applications. Furthermore, there exists a need for materials for holding the PCM that optimizing the performance of the PCM in regulating and managing temperatures.